The invention relates to a keeper and cam end of a cam, or overcenter, type door fastener, which provides means for sealing or locking the keeper to the cam end whereby unauthorized opening can be detected or prevented.
The invention is an improvement to a door latching system, such as is described in U.S. Pat. No. 1,925,234 issued Sept. 5, 1933, to Charles E. Dath, assigned to the assignee of this invention and incorporated herein by reference. This type of door latching system is sometimes referred to as an overcenter type fastening mechanism in which a cam end rotates into a fastened position with a cooperating keeper affixed to the door. The cam end is an axial extension of a rotatable shaft, or bar. The rotatable shaft is urged into and out of the cam-type keeper engagement by means of a lever arm.
In normal practice, two rotatable shafts, each having two of the cam ends, are provided for a double-door trailer, cargo container, refrigerator car, and the like. The overcenter type cam action is particularly suitable for such containers, inasmuch as the engagement with the keeper is obtained by pivoting of the cam end. A larger lobe of the cam end engages a recess of the keeper; and as the lever arm rotates in the direction of the door, the large lobe of the cam bears against the keeper recess until the lever handle fully rotates to generally contact the face of the door. At this point, an opposing smaller lobe of the cam end is nested within a forward-opening receiving slot of the keeper. Thus, it will be understood that engagement with the keeper is achieved before the door is fully closed. The cam action draws the door, during its rotation, into a secured position. Even if the lever arm is not fastened to the front surface of the door, by some releasable locking means or the like, the door is yet prevented from opening due to the locking action of the cam end with the keeper.
Other styles of door fasteners, which do not utilize the locking cam action as described, are susceptible to being opened should the lever arm not be secured to the door. This presents a clear vandalism, or theft, problem inasmuch as a simple disengagement of the lever arm, by burglary tools or the like, would grant access to the interior of the cargo container in a very few seconds. Likewise, in the non-camming, non-overcenter type fasteners, should the lever arm accidentally or otherwise be disengaged from the door, the shifting of the cargo load against the doors within the container could easily rotate and open the doors. In the very least, such accidental movement could break the frangible seal usually provided on the fastener and give a false indication of tampering or allow subsequent tampering or theft to go undetected.
One previous provision for securing a door fastener is shown in U.S. Pat. No. 3,572,794, issued to Pastva. A latch member, having two forks, engages projecting portions of a keeper. A vertical pivoting latch is provided to secure one of the forks in a slot of a corresponding projecting member. The latch, however, does not function to prevent or deter opening, but is provided for the practical reason that the latch members at the end of the rotatable bars do not lock with the keeper in an overcenter condition. Without the latch member, the bar end could rotate and disengage from the keeper when an internal force inside of the container pushes the door outwardly. Furthermore, even if the latch and fasteners, which provide no overcenter arrangement, were separately secured to the keeper, such as by a locking pin or the like, the latch would be the only securing force for the rotating bar if the lever arm became disengaged. In the previously mentioned cam-type fastener, the cam end and keeper are in a locked condition at full door closure, distinct from being otherwise locked by a latch. Thus, an inherent safety feature is provided in this type of fastening arrangement. It would, however, be desirable to also eliminate, or at least greatly reduce, the tamperability, or susceptibility to unauthorized opening of the fastener, in addition to providing the cooperative locking effect of the cam end.
It is accordingly the primary goal of the invention to provide a fastener for doors and the like with means for detecting vandalism, preventing unauthorized opening, or both.
It is an important goal of the invention to provide such anti-tampering and anti-theft means without essentially deviating from the effective cam end and keeper locking provisions on the fastener, such as shown in the above-cited U.S. Pat. No. 1,925,234.
It is accordingly a goal of the invention to maintain an overcenter type fastening for doors and the like by providing means for securing a seal in cooperation with the cam end and keeper, which is protected from accidental opening and which, if broken, would be easily detected by visual inspection.
It is a concomitant objective of the invention to provide such an overcenter type fastening device with means in which a padlock, or the like, can be readily received to offer a secure deterrent to unauthorized opening.
It is further a goal of the invention to provide such means whereby both a seal and a lock, such as a padlock or the like, may be used together for both the detection of tampering and for the prevention of unauthorized opening.
Accordingly, the invention entails, in brief summary, an improving modification to cam end and keeper fasteners, such as shown in said U.S. Pat. No. 1,925,234, and further as shown in my co-pending U.S. patent application Ser. No. 369,538. The improvement generally comprises a co-extensive extension of keeper projections, which are spaced apart for receipt therebetween of a second cam lobe of the end member of a rotating shaft. In the preferred embodiment, the extended keeper projections and the lobe member are further formed to wedge together to provide a secure engagement, which stabilizes the fastener and substantially prevents tampering with the fastener. The co-extensive extended keeper projections and the cam lobe are provided with alignable seal and lock receiving means through which a government seal, locking bolt, padlock, or the like, can be extended to seal or lock the fastener in a closed position.